If laws are just made up, then why do we have to follow them? What normative force do they have? It has seemed to most philosophers of law for the last two centuries that law either has moral or prudential normativity, or that it has no normativity at all. As a result, the normativity of law has seemed to be a serious obstacle for theories that attempt to explain law as a social phenomenon, explicable with descriptive resources. But this obstacle can be overcome. The central claim of my dissertation is that law—and other normative practices, such as language and games—are normative in an alternative, non-moral and non-prudential, fashion. As a result, it is possible to explain this normative practices by appeal to descriptive states of affa...